The interactions between N-Octyl-β-D-glucopyranoside (OGP) and bovine serum albumin (BSA) have been investigated by fluorescence, ultraviolet spectroscopy and surface tension measurements. The surface tension curve of the OGP solution can be modified by the addition of BSA. From the surface tension curve of the OGP solution and OGP/BSA solution, we can see that the critical micelle concentration of OGP in OGP/BSA solution is bigger than in OGP solution. This is because that the concentration of OGP monomer is decreased by the binding of OGP molecules on the surface of BSA. It was found that the presence of protein delays the surfactant aggregation by using the pyrene 1∶3 ratio method. The reason is same with that of the surface tension change. The fluorescence intensity and ultraviolet absorption intensity of BSA gradually decrease upon increasing the concentration of OGP, and a blue shift of the max fluorescence emission wavelength of BSA was observed, this indicated that OGP mainly interacts with Trp residues compared to Tyr residues. The results from synchronous fluorescence spectrum and I^－ quenching experiments also indicated that OGP mainly interacts with Trp residues of hydrophobic loop.

Key words: N-Octyl-β-D-glucopyranoside, surface tension, fluorescence, ultraviolet absorption, bovine serum albumin (BSA)